Recommended to aid inflation and decrease rapid air loss known as “”burping”” which occurs under hard cornering, off-camber riding or similar situations when using rims not intended for use as tubeless. 29ER Fits most 29er rims measuring 25-28mm externally 32mm Presta valve has removable valve core for sealant installation Standard For 24" and 26" rims measuring 21.5-24.5mm externally May also fit some narrower 29er Rims DH Fits most 24 and 26" rims measuring 36-39mm externally 32mm Schrader valve has removable valve core for sealant installation